1. Field of the Invention
The invention relates to a method for distributing frame synchronization information at a base station implementing air interfaces of at least two different standards and to a base station implementing air interfaces of at least two different standards.
2. Description of the Related Art
A base station, or base transceiver station, or node B (a term used by the European Telecommunications Standards Institute, ETSI) is a network element in a mobile network responsible for radio transmission and reception to or from the mobile station. The base station provides the transceiver functions of the base station system. One base station may include one or more transceivers. In third generation networks, the base station terminates an Iub interface towards a radio network controller (RNC).
Traditional base stations only implement an air interface of a certain standard, such as GSM (Global System for Mobile Communications) or UMTS (Universal Mobile Telecommunications System). In such base stations the distribution of frame synchronization information usually utilizes a continuous frame clock signal in a bus. The distribution is relatively unproblematic to implement as frame synchronization information of only one standard is transferred in the bus.
However, nowadays base stations that implement simultaneous air interfaces of at least two different standards are becoming more common. The distribution of frame synchronization information at such ‘multi-standard’ base stations is much more complicated than at a traditional base station.